Specialty Testing Guide › TruHealth Micronutrient Testing
Most healthy adults who eat a reasonably varied diet do not need a daily multivitamin. Large studies and the US Preventive Services Task Force have not found good evidence that multivitamins prevent heart disease, cancer or early death in the general population.
That does not make every supplement useless. Specific groups, such as people who could become pregnant, older adults, vegans and people who have had weight-loss surgery, benefit from targeted nutrients for clear reasons. The smarter question is not "should I take a multivitamin" but "do I have a specific gap, and how would I know?"
Key takeaways
- The USPSTF says the evidence is too thin to judge whether multivitamins prevent heart disease or cancer.
- The task force advises against beta-carotene and vitamin E supplements for that purpose.
- A study following almost 400,000 healthy US adults for up to 27 years found no lower death rate among daily multivitamin users.
- Targeted nutrients make sense for pregnancy planning, older age, vegan diets, weight-loss surgery and proven deficiencies.
What the evidence says about multivitamins
About a third of US adults take a multivitamin, most often for general wellness or to fill gaps in the diet.12 The question researchers have tried to answer is whether that habit prevents the diseases that matter most.
In 2022 the US Preventive Services Task Force reviewed the trials and concluded that the current evidence is insufficient to assess the balance of benefits and harms of multivitamins for preventing cardiovascular disease or cancer.1 It reached the same conclusion for most single nutrients and nutrient pairs.
To be fair to multivitamins, the evidence review behind that statement found a possible small reduction in cancer among multivitamin users, but the studies had important limitations, and no clear effect on heart disease or death.3
Long-term observational data point the same way. In three large US cohorts followed for up to 27 years, people who took a multivitamin daily did not have a lower risk of death than people who did not.2 Multivitamin users also tend to have healthier habits overall, which makes it harder, not easier, to show a real benefit from the pill itself.
Supplements the task force advises against
Two supplements stand out for the wrong reasons. The USPSTF recommends against beta-carotene and vitamin E supplements for preventing heart disease or cancer. For beta-carotene, it found the harms outweigh the benefits, and trials linked it to more lung cancer in people already at high risk, such as smokers.13 For vitamin E, it found no net benefit.
The lesson is that antioxidant-sounding labels are not evidence. Some nutrients that look helpful in lab studies have done nothing, or caused harm, when tested in people.
Who does benefit from targeted supplements
Several groups have good reasons to take a specific nutrient:
- People who could become pregnant. The USPSTF recommends a daily folic acid supplement for everyone planning to or able to become pregnant, to prevent neural tube defects.4 It carries an A grade, the task force's strongest rating.
- Adults over 50. Absorption of B12 from food often falls with age, so B12 from fortified foods or a supplement is advised.5 Our guide to B12 deficiency risk factors explains who is most affected.
- Adults over 75. The Endocrine Society suggests vitamin D above the standard intake for this age group, without the need for testing. See our guide to vitamin D in Pennsylvania for how winter sunlight factors in.
- Vegans and strict vegetarians. B12 comes almost only from animal foods, so a supplement or fortified foods are needed.
- People who have had weight-loss surgery. Surgery changes absorption, and lifelong supplements and regular blood tests are standard care.
- Anyone with a confirmed deficiency. A specific nutrient, at a dose set by your clinician, for a set period, with a recheck.
When a multivitamin can cause problems
A basic multivitamin at label amounts is unlikely to harm most adults. Trouble usually starts when products stack up. Common problems include:
- Iron in a multivitamin for men and postmenopausal women who do not need it
- Vitamin A, vitamin D and other fat-soluble vitamins building up when several products overlap
- Biotin, often in hair and nail formulas, interfering with some lab tests, including common thyroid tests6
- Vitamin K changing how warfarin works
Bring every bottle, or a photo of each label, to your next visit. Your clinician can spot overlaps quickly.
Testing before supplementing
If you suspect a specific gap, a standard blood test usually answers it. Iron studies, B12, folate and vitamin D (when there is a reason to check) are routine and widely available.
Some people want a broader view. TruHealth from TruDiagnostic estimates many nutrient-related markers from DNA methylation patterns rather than measuring nutrient levels in blood directly. It can be one input in a wider review, but any low estimate should be confirmed with a standard blood test before you start a high-dose supplement.
Your next step
If you are planning supplements after any kind of testing, read supplement safety after testing to see which nutrients carry real risks at high doses. The micronutrient testing hub has the full series.
Frequently asked questions
Is a multivitamin a waste of money?
For most well-nourished adults, the evidence does not show a disease-prevention benefit. It may still make sense in some situations, such as a very limited diet, but it is no substitute for testing if you suspect a real deficiency.
Are expensive or "food-based" multivitamins better?
There is little evidence that premium brands improve health outcomes compared with standard ones. Third-party quality seals, such as USP Verified, show that a product contains what the label says, which is a more useful thing to check than price.
Should I stop my multivitamin before a blood test?
Some ingredients, especially biotin, can affect certain lab results. Ask the clinician ordering your test whether to pause anything beforehand.
Related reading
This article is for general education and is not medical advice. Decisions about testing and treatment should be made with your clinician. If you have severe symptoms, call 911. For a suspected poisoning, call Poison Control at 1-800-222-1222.
